Fuse block and receptacle mounted on bus bars



Sept. 26, 1950 J. M. WALLACE ETAL Fdsz BLOCK AND RECEPTACLE MOUNTED on BUS mas Filed Jan. 25, 1945 |NVENTOR5 J5me: AVh/x and .WITNESSES:

Patented Sept. 26, 1950 FUSE BLOCK AND RECEPTACTE MOUNTED ON BUS BARS James M. Wallace, Braddock, and Andrew W. Edwards, Wilkinsburg, Pa., assignors to West inghouse Electric Corporation, a corporation of Pennsylvania Application January 25, 1945, Serial No. 57 4,482

5 Claims.

. This invention relates, generally, to electric circuit interrupting devices and, more especially, to novel fuse and fuse mounting constructions.

This invention is hereinafter particularly .disclosed in connection with small, three-phase, low-voltage fuses particularly adapted for use .in protecting low voltage networks such as used in aircraft, where space and weight are important considerations. It will be obvious, however, that at least some features of the invention will be useful in other locations as multi-phase protective devices, and that certain features of the invention will be of utility where either space or Weight considerations are of importance.

One object of this invention is to provide a novel multi-phase fuse construction having a single fuse holder or container.

Another object of this invention is to provide a "novel indicating fuse construction.

Another object of this invention is to provide a novel mounting or supporting structure for multi-phase fuses.

Another object of this invention is to provide a novel shock and vibration-proof fuse mounting.

Another object of this invention is to provide a novel fuse supporting means especially adapted for mounting on a bus structure.

Still another object of this invention is to provide a novel fuse structure which is small in size and light in Weight, and yet Which is efficient t in operation.

These and other objects of this invention will become more apparent upon consideration of the following detailed description of a preferred embodiment thereof, when taken in connection with the attached drawing, in which:

Figure 1 is a perspective view of a fuse, its mounting, and arrangement for supporting fuses on bus bars, with one fuse removed from its mounting;

Fig. 2 is a transverse section view through a it will be apparent, as hereinafter pointed out,

that certain features of the invention may be embodied in single-phase constructions, or in constructions having any desired number of phases.

The fuse 2 illustrated on the drawing (Fig. 3)

comprises a casing having opposed side walls 4,"

end walls 6, and a bottom wall 8, which may all be of integral construction, preferably of an integral molded insulating material. Three fuse strips ID are supported in the fuse casing in spaced relation with each other, and spaced from the bottom wall 8. Fuse strips 10 are provided with wide'end portions l2 which are preferably molded in opposite side walls 4 of the fuse casing, and extend outside of the casing where they are bent over against the outside of the casing to form fuse terminals M. For the purpose of aiding in extinguishing the are upon fusion of fuse strips 10, the casing is filled with a finely divided inert insulating material, such, for example, as sand.

In order to provide a visible indication when the fuse blows, a transparent top wall I8 is provided, and high resistance fusible indicating strips 20 are located in engagement with the inner side of transparent wall l8. Indicating strips 20 may be of any desired relatively high resistance material, such, for example, as brass, steel, or aluminum, being very thin, on the order of .001 inch. .In assembling indicating strips 26 and transparent wall l8, it is preferred to temporarily secure the indicating strips 20 to the inner side of wall 18, for example, as by cement or the like, with the indicating strips 20 properly positioned sothat when wall I8 is assembled with the casing to the position shown on the drawing, the ends of indicating strips 20 will engage the upper edges of the wide ends l2 of fuse strips 10, respectively. Transparent wall 18 may be secured in position in any desired manner, preferably by a sealing material 22. Opposite end walls 6 of fuse 2 are provided with integral locking projections 24, and one end wall 6 is provided with spaced manipulating projections 26, for a purpose which will be described. Projections 24 and :26 are preferably molded integrally with the casing 2.

In the operation .of the fuse 2, it will be apparent that upon the passage of excessive currents through fuse strips H], the central part of the strips will .melt, leaving indicating strips 20 across the circuit. Inasmuch as indicating strips 20 are of a relatively high resistance and do not normally carry any substantial part of the current,ithey'will immediately be melted, thus providing .a readily visible indication of the blown condition of its associated fuse strip through transparent wall 18. Since fusible strips 1'0 are embedded in finely divided insulating material I 6, the are formed upon fusion thereof will be rapidly extinguished.

The particular fuse structure 2 thus provides a multi-phase fuse in a single container, to afford a particularly compact arrangement occupying but a relatively small space.

Fuses 2 are adapted to be supported in a multiphase fuse holder, such as the holders 28, each of which comprises a base portion 30, having an end wall 32 at one end thereof, and an end ledge 34 at the other end thereof. Fuse holder 28 is also provided with opposite side portions 36, and

although these parts, as well as end wall 32 and ledge are shown as separate elements suitably secured together, they may, if desired, all be integral with base 30, as by being integrally formed of a molded insulating material.

The underside of base 30 of fuse holder 28 has a longitudinally extending supporting projection 33 integral therewith, through which mounting apertures 45 are provided, for the reception of mounting screws or the like to mount holder 28 by securing base 35 to any suitable support. End wall 32 of fuse holder 28 is also. provided with a mounting aperture 42 for use when it is desired to mount the fuse holder by securing end wall 32 to a suitable support, such, for example, as a support which extends in a vertical direction or the fuse may be mounted on a horizontal surface with this end down and thus furnish support for bus cars running parallel to the horizontal surface. Mounting apertures 40 of the fuse holder may advantageousl be used when it is desired to mount the fuse holder on a horizontally extendin support, when the unit is used separately and not connected with bus bars, as will be described.

Each fuse holder 28 is provided with a plurality of spaced contacts 44 mounted on each side 35 thereof. Each of contacts 44 comprise a contact strip 45 of good electrical conducting material, such for, for example, as copper or the like, and a resilient backing strip 48 of some resilient material, such as steel, or Phosphor bronze. As shown more particularly in Fig. 2, the inner ends of contact strips 46 and backing strip 48 of each contact 44 are secured together to the outside of holder side wall 36 by a terminal screw 50 which threadedly engages in an insert molded in sides Each insert has a head 52 at the inner side of each side 35 of the holder at a position where the insert is positively prevented from turning by engagement of head 52 with base 30 cf the holder. The outer end of each contact strip and its backing strip 48 of each contact 44 are directed angularly inwardly, and the outer end of contact strip 46 is bent over the outer end of backing strip 48 as at 47, to secure the outer ends of the strips together. Sides 36 of fuse holder are provided with integral insulating barrier projections 54 at each side of contacts 44, and supporting projection 38 on base 30 provides electrical clearance between the contacts 44 at opposite sides of fuse holder 28.

End wall 32 of fuse holder 28 is provided with an opening 56 for cooperation with a locking projection 24 at one end of a fuse 2, and a spring retainer strip 58 is provided at the other end o the holder, having an angularly extending end '68 thereof secured to the underside of base 363. Retainer strips 58 is provided with an opening 62 adjacent the outer end thereof for cooperation with the locking projection 24 at the other end of fuse 2.

A fuse 2 may be readily inserted in a holder 28, by positioning locking projection 24 in aperture 55 of end wall 32 of the holder, and grasping the fuse 2 at the end thereof having manipulatin projections 25, while rotating the fuse to bring locking projections 24 at this end into engagement with the outer end of retainer strip 58, until projection 24 on the fuse snaps into opening 62 of the spring retainer strip. It will be noted that the outer end of retainer strip 58 is curved outwardly, so that in inserting fuse 2, the projection 24 at the same end of the fuse with projections 26 will engage the outer end of retainer strip 58 and cam it outwardly, until locking projection 24 slips into aperture 62. When fuse 2 is operatively associated with a fuse holder 28 in the manner described above, the end thereof having manipulating projections 2'? will rest on end ledge 34 of the holder. Moreover, it will be noted that this mounting for fuse 2 is vibrationand shock-proof, because of the positive engagement of locking projections 24 in openings 56 and 62.

When a fuse has blown and it is desired to remove fuse 2 from its mounting 28, this may be easily done by merely moving retainer strip 58 outwardly to disengage locking projection 24 at this end of the fuse, and then lifting this end of the fuse upwardly by means of manipulating projections 25 until this end of the fuse clears retainer strip 58, and then the fuse locking projection 24 at the other end may be withdrawn from aperture 56. It will be observed that fuse 2 is very easily inserted or withdrawn from fuse holder 28, and that this may be done without the necessity of touching any live parts.

In Fig. i of the drawing, there is illustrated a pair of fuse holders 28 and the particular manner in which they may be mounted on a supporting panel or the like 68 for supporting bus bars 64 of a source of supply of three-phase electrical energy. Fuse holders 28 are mounted on panel 68 by screws 43 located in mounting apertures 42 of each holder, to secure end wall 30 of each holder to panel 68. For the purpose of mounting bus bars 64 on fuse holders 23, the bus bars are provided with openings which may be in the form of laterally'extending notches 66, for receiving terminal screws 50 of the fuse holders, so that when the screws at one side of the fuse holder are positioned in notches S6 and tightened, the bus bars will be mechanically supported from, and electrically connected with the fuse holders. Moreover, the terminal screws 50 at the other side of the fuse holders will be exposed for the connection of branch circuits thereto. In order to provide for more compact arrangement, it is preferred that where a plurality of fuse holders are to be employed, that they be mounted in staggered relation as illustrated in Fig. 1, with adjacent holders projecting from the bars in opposite relation.

As previously stated, the embodiment of the invention disclosed above is especially constructed for a three-phase system, such, for example, as the three-phase network systems used on aircraft or the like. In such a system, space and weight are very important factors; and the invention, therefore. provides a particularly compact arrangement for connecting branch circuits with the supply bus bars of such networks. As an example of compactness and small size of the arrangement disclosed herein; for a -220 volt, three-phase network, the fuse casing 2 need be only 2 inches long, 1 inch wide, and about 2; inch deep, and the fuse elements l5, holder contacts 44, and bus bars 64 have half-inch spacing from center to center. Moreover, holders 2% may be mounted with one-inch spacing between mounting slots 65 on the bus bars. Fuses of this size may be rated at least up to 30 amperes continuous current-carrying capacity, at 110 and 220 volts, and are capable of interrupting at least 4,000 B. M. S. amperes.

Although one particular fuse structure, fuse holder, and mounting therefor for one particular application have been given wherein the particular structure and arrangement described have certain novel features of cooperation which give rise to certain novel functions, it will be apparent that the structure disclosed can be used for other ratings by merely changing the size of the fuse elements and certain of the other parts, and that the units, comprising a holder 28 and a fuse 2 may be used separately, and separately mounted either on a horizontal support by means of mounting apertures 48, or on a vertical support by means of aperture 42, instead of serving as mountings for bus bars, as illustrated. In any event, it is apparent that the mounting of fuses 2 in holders 28 provides a shock-proof and vibration-proof mounting, which is relatively simple to manipulate to insert or remove a fuse from holders 28. Moreover, certain features of the invention might obviously be employed in singlephase constructions, or in any plural-phase construction other than the three-phase structure illustrated.

Having described a preferred embodiment of the invention in accordance with the patent statutes, it is desired that this invention be not limited to this particular structure inasmuch as it will be apparent, especially to persons skilled in the art, that many modifications and changes may be made in the structure herein disclosed without departing from the broad spirit and scope of this invention. Therefore, it is desired that the invention be interpreted as broadly as possible, and that it be limited only as required by the prior art.

We claim as our invention:

1. Ina multi-pole fuse construction, a fuse container, a plurality of fuse elements supported in spaced insulated relation in said container, spaced opposed terminal parts supported on the outside of said container on one pair of opposite side walls thereof in insulated relation for each of said fuse elements, each of said fuse elements connected between its corresponding opposed terminal parts, a holder for said fuse container comprising a base member, a number of spaced opposed resiliently biased contacts corresponding to the number of fuse elements in said container, said contacts mounted on said base in insulated relation, and'said base having means engaging the opposite end walls of said container which connect said opposite side walls for detachably securing said container to said base with said container located between said opposedconta-cts, and with said contacts resiliently engaging said terminals, respectively.

2. In a multi-phase fuse mounting, a supporting base of insulating material, a plurality of pairs of opposed resiliently biased contacts-secured at opposite sides of said base and extending upwardly therefrom, retaining means extending upwardly from opposite ends of said base, a multi-phase fuse unit having a plurality of pairs of opposed terminals at opposite sides thereof for engagement with said contacts, respectively, when said fuse unit is inserted downwardly therebetween, and said retaining means positioned to engage opposite ends of said fuse unit, respectively, with one of said retaining means being resiliently biased into engagement with said fuse to releasably maintain said fuse unit in operative relation with said base.

3. In a multi-phase fuse mounting, a supporting base of insulating material, a plurality of pairs of opposed, resilient biased contacts secured at opposite sides of said base and extending upwardly therefrom, said base having retaining portions extending upwardly at opposite ends of 4. In apparatus. of the type described, a multiphase source of electrical energy comprising a plurality of bus bars, means for connecting a plurality of branch circuits to said source comprising a unitary multi-phase fuse structure for each branch circuit, each of said structures having terminals rigid therewith at opposite sides thereof, means for securing all of the terminals at one side of each fuse structure directly to said bus bars, respectively at points intermediate the ends of said. bars with said structure projecting later ally from said bars to rigidly connect said structure to said bars, and with adjacent ones of said fuse structures being spaced longitudinally of said bars and projecting laterally in opposite directions from said bars, whereby the terminals at the other side of each structure are accessible for connection to branch circuits.

5. In apparatus of the type described, a multiphase source of electrical energy comprising a plurality of bus bars, means for connecting a plurality of branch circuits to said source comprising a unitary multi-phase fuse structure for each branch circuit, each of said structures having terminals rigid therewith at opposite sides thereof, means for securing all of the terminals at one side of each fuse structure directly to said bus bars, respectively, at points intermediate the ends of said bars with said structure projecting laterally from said bars to rigidly connect said structure to said bars, and with adjacent ones of said fuse structures being spaced longitudinally of said bars and projecting laterally in opposite directions from said bars, whereby the terminals at the other side of each structure are accessible for connection to branch circuits, and means engageable with corresponding ends of each of said fuse structures for supporting said fuse structure and bus bars.

JAMES M. VVALLIACE. ANDREW W. EDWARDS.

REFERENCES CITED The following references are of record in the file of this patent:

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